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By E. J. Gleim

An important phase in the Bureau of Mines investigation of electrical machines designed for operation in gassy coal mines is testing enclosures of electrical components for explosion-proof qualities. In brief, this testing consists of filling and surrounding the enclosure with an explosive atmosphere of methane and air and then igniting the atmosphere within the enclosure to determine (1) Whether the resulting explosion is confined without discharge of flame; (2) whether the enclosure walls are permanently distorted; and (3) whether excessive pressures are developed within the enclosure. Ordinarily, the pressures encountered in routine testing do not exceed 100 pounds per square inch gage. Hence, the designer of the machine does not have too much difficulty in taking corrective measures to prevent flame discharge and distortion of the enclosure. Occasionally, however, the explosion pressures greatly exceed 100 pounds. Then the goblet of the designer may not be solved so readily, From experience over the year 0, the testing personnel often can predict that certain construction will result in high. Pressures, but, only in a very general way, has it been possible to advise designers what modifications might be made to reduce the explosion pressures to normal values. For example, if high pressures were developed in a motor starter having a partition with an opening through it, some enlargement of the opening may appear to be the logical procedure, but it has not been- possible to give information concerning the exact amount the opening should be enlarged to prevent development of high pressures .

Jan 1, 1952

By Lulie H. Crump

Salient information on reserves, production, and consumption of fuels and energy by State is summarized in this Bureau of Mines publication. Reserve and production data are shown for each of the fossil fuels (coal, crude oil, natural gas liquids, and natural gas) and for uranium. The consumption data of each of the major consuming sectors (household-commercial, industrial, transportation, electric power, and miscellaneous) are broken down by energy source (coal, petroleum, natural gas, hydropower, and nuclear). In addition, total energy consumption in the Nation in 1973 is compared with consumption in 1972 and 1974 (preliminary data).

Jan 1, 1976

By Mark S. Stagg

Blast-induced ground vibrations from surface coal mine, quarry, and construction blasting were measured and analyzed for frequency content and duration characteristics. Eighteen commercially available ground vibration measurement systems were evaluated in the field and laboratory for linearity, accuracy, and crosstalk. Buried, surface, and sandbagged transducer placement methods were compared, along with peak and vector-sum measurements. The recommended minimum frequency ranges for ground vibration instrumentation are 2 to 150 Hz for coal mine and quarry blasting, and 5 to 200 Hz for construction and excavation blasting. When higher or lower frequency vibrations are possible, as in construction blasting or for a quarry shot close to a residence, care should be taken to insure proper choices of instrumentation and vibration criteria. Several instruments operating in these ranges are available, and all but one of the seismographs tested fell within ±3-dB accuracy limits (+41 pct, -29 pct). Waveform recordings of all three ground vibration components are recommended as the peak amplitude and frequency may vary among the three. Peak or vector-sum readings are adequate if only amplitude levels are desired. The soil density matched box should be anchored or buried, particularly for high-frequency, high-amplitude construction blasting.

Jan 1, 1980

Reduce respirable dust exposure of workmen operating auger-type continuous mining machines. Approach: An auger miner was fitted with an exhaust system which draws dust laden air through a [scruber] and discharges it behind the line curtain. How It Works: Dusty air is drawn into the space above the coal conveyor and through a scrubber, by two fans mounted side by side above the conveyor. Exhaust from the fans passes through a duct to the side of the auger miner, and into tubing that runs back and into the air return passage formed by the line curtain. See Figure 1. Of the 5,000 cubic feet per minute of air normally entering the working place, 4/5 is drawn out through the dust exhaust system. The system was installed on a Wilcox Mark 20 Miner and tested underground by personnel of the Bureau's Pittsburgh, Pa., Mining and Safety Research Center, under a cost sharing

Jan 1, 1976

By William R. Archibald

This report presents the results of a program demonstrating the technical and economic feasibility of hydraulic borehole mining of uraniferous sandstone. This mining technique involves the drilling of a borehole from the surface down into the ore body. A borehole mining tool consisting of a high-pressure cutting jet and a slurry jet pump is lowered down the borehole. Water from the high-pressure cutting jet cuts into the sandstone formation generating a water-sand slurry which flows to the slurry jet pump and is pumped to the surface. The cutting jet is rotated and moved up and down from the surface, thereby generating a cavity in the formation. When the cavity size reaches a point beyond the effective radius of the cutting jet, the mining tool is moved to an adjacent borehole and the process is started again. This program was carried out in four phases. Phase I included modifications to the borehole mining system (built and tested under a previous contract, No. H0252007, for the mining of coal) and factory tests of the jetting system. Phase II covered the field tests and a public demonstration. Phase III involved nozzle and equipment modifications and factory tests. Field testing continued under Phase IV along with an evaluation of this method. The field tests were conducted successfully on Rocky Mountain Energy Company's Nine Mile Lake property near Casper, Wyoming. Results indicate that; hydraulic borehole mining of uranium is technically feasible (300 tons of uraniferous sandstone were mined from a depth of 90 ft) and the hydraulic borehole method is economically attractive. However, additional testing is required to clearly define the economic feasibility.

Jan 1, 1978

By Richard Mainiero, Donald A. Hurd, James H. Rowland

In previous conferences the authors have reported on toxic fumes generated by the detonation of ANFO. The research reported here extends the earlier work to include an emulsion blasting agent and ANFO/emulsion blends. Explosive mixtures were shot in 4-inch Schedule 80 steel pipe in a chamber in the experimental mine at the Pittsburgh Research Laboratory (PRL). Following each shot, the fumes in the chamber were analyzed using on-line instrumentation. A major goal of the research was to gain a better understanding of the factors that lead to the generation of toxic fumes in blasting operations. Earlier studies have suggested that the high nitrogen dioxide and nitric oxide concentrations in product clouds might be the result of the poor confinement provided by relatively weak ground strata or the exposure of the explosive to ground water prior to shooting the shot. Various mixtures of ANFO and emulsion were detonated in schedule 80 steel pipe and galvanized sheet metal pipe to evaluate the effect of confinement. Explosive mixtures were also allowed to soak in water for less than one day, one week, one month, and two months to determine which explosive mixtures would be degraded and observe what effect this degradation had on fume production. Results indicated that the production of nitrogen dioxide increased with low confinement of the detonating explosive and with exposure of the explosive to water.

By Dale R. Ralston

This investigation was divided into two major phases. Phase I of the study was an examination of the occurrence and production of acid water within the Bunker Hill Mine in northern Idaho. The second phase of the project involved the study of water movement through an abandoned tailings pile. Mineralogy and hydrogeology were determined to be the two most important factors in the acid mine drainage problem. Low pH water was formed in the mine in areas of lead-zinc ore rich in pyrite. Water movement in the mine was important in the production of acid and the transportation of heavy metals. Areas of recharge to the mine were identified. A data collection network was installed to monitor water quality and quantity changes. The quantity of acid drainage from the mine was found to vary directly with surface runoff events. The study of the abandoned tailings pile was performed to determine the characteristics of water movement through the tailings material and the resultant impact on the hydrologic environment. The Page Tailings Pile, abandoned in 1969, was utilized as a study area. An extensive network of piezometers and meteorological data collection sites were installed in and near the pile. Data collected to date indicate the presence of a ground-water mound under the east half of the pile. Some transfer of ions from the tailings pile to the ground-water system has been detected.

Jan 1, 1973

By L. B. Berger

The Haldane gas-analysis apparatus used by the Bureau of Mines is patterned after the device developed by Haldane 4/ and differs from it only in structural modifications that have been added to facilitate operation and simplify construction. The apparatus was developed to permit determination of carbon dioxide, combustible gases, and oxygen with a degree of accuracy not attainable with apparatus of the types ordinarily used for the analysis of fuel gases, flue gases, and similar mixtures. The Haldane apparatus is used by the Bureau of Mines chiefly in the analysis of air samples collected in coal and metal mines and other underground workings and is applied also in the analysis of many other types of gas mixtures when accurate determination of certain constituents is desired.

Jan 1, 1938

By J. L. Holman

The Bureau of Mines, at its Rolla Metallurgy Research Center, has devised methods for separating and reusing the major portion of waste plastics discarded in urban and industrial refuse. Waste plastic concentrates from a local collection drive, recycling center collections, urban refuse pilot plants, and the secondary metals industry were separated into three major thermoplastic families--polyolefins, styrenes, and vinyls--based on differences in density using a Bureau-designed sink-float-elutriation hydraulic separator. Other separation methods and systems such as air classification, jigging, liquid media, screening, and electrostatics were studied. Vinyl plastics contain up to 50 percent HC1. It was found that over 90 percent of the HC1 in vinyls can be recovered as usable hydrochloric acid by pyrolysis at 350° C. The remaining pyrolysis products which had heats of combustion in excess of 12,000 Btu/lb, could become valuable as a future source of energy. A characterization study conducted on eight chopped wire insulation wastes from secondary copper and aluminum processors showed that most wastes contained 2 to 7 percent residual metal and large percentages of vinyl. The residual metal content of some of these wastes was lowered to 0.1 percent and the vinyl portion segregated using various separation techniques. The research also suggests ways in which reclaimed thermoplastics may be fabricated into useful products.

Jan 1, 1974

By K. L. Bainbridge

This report describes the results of a study to determine which types of, and to what extent, mining wastes can contaminate groundwater through leaching of acid-forming or potentially toxic constituents. The primary focus of this study was on coal mining wastes, especially overburden spoils and preparation plant refuse. In addition, the potential for contamination by leachates from clean coal stockpiles was also examined. The study approach included investigation of (a) the amounts and geographic locations of mining wastes in the United States; (b) the chemical character of mining wastes, especially with regard to potentially acid-firming or toxic constituents; and (c) the extent to which acid and/or toxic components are leached from mining wastes by rainwater. To evaluate the leachability of coal wastes, a laboratory waste leaching method was developed during this study to specifically simulate the leaching process over a long-term. Waste samples collected during this study were also leached by the EPA extraction procedure and ASTM waste leaching method. Results of the three leach test methods were compared to evaluate their relative capabilities to predict the leachability of mining wastes.

Jan 1, 1980

This study of underground mine water inflow was initiated by the U. S. Bureau of Mines in March 1980. The objective of this study is to evaluate the hydrologic variables associated with surface water and ground water systems that affect the inflow of ground water into an underground mine. Data collection techniques are reviewed for their applicability for quantifying these hydrologic variables. Innovative techniques are also investigated. Existing analytical and numerical procedures for predicting underground mine water inflow are reviewed and evaluated. Over 300 computer models were reviewed for their applicability to modeling underground mine water inflow. The model UNSAT2 is utilized for modeling inflow to a shaft and tunnel or drift. This model and the techniques developed in this study are applied to two existing mines.

Jan 1, 1982

By BUREAU OF MINES

Mercury has been used by mankind since prehistoric times. It has been, and is now, widely used in industry and medicine and has unique properties which make direct substitution difficult or impossible. At present its prin- cipal uses are for electrical apparatus, control instruments, electrolytic soda preparation, mildew-proofing paints, pesticides, and medical and dental preparations. Deposits of mercury are less common than those of other base and precious metals, but some of the deposits are very large and have been ample to meet the world's past demands. The price of mercury has had many sharp fluctua- tions, but in general, the limited number of producers has resulted in a more stable price structure than that of many other commodities. The United States has been one of the main producers of mercury, and from 1850 to 1961 produced 3,247,704 flasks. Yearly production since World War II has varied from 4,535 to 38,067 flasks. An estimate of domestic resources of mercury producible at various price ranges was prepared for each mercury mine by combining specific knowledge of mercury mineralization with estimates of potential, based on geologic informa- tion and past production history. The sum of the individual estimates for each price range is shown in a table. A parallel estimate of nationwide production potential was made from a study of past price and production relationships. These were analyzed by plotting yearly production figures against the previous year's price, expressed in dollars of constant purchasing power. An equation was fitted to the data by mathematical means and was used to extend the curve into areas of higher than historic prices. Potential production rates at various price levels were taken from this graph. The estimated yearly production rates were used to make an estimate of total potential based on the premise that produc- tion rates and reserves have a proportionate relationship.

Jul 1, 1964

By Corale L. Brierley

Beneficiation of phosphate in the southeastern United States generates a slurry of finely divided clay. These clay-wastes are impounded to allow the particulates to settle. The aggregation of phosphatic clay-slime wastes and slimes produced from potash beneficiation by microbial processes was studied using several bacterial species known to produce polymeric substances. Experiments included flocculation capacity of clay-slimes by whole cells, the determination of respiratory activity of whole culls in the presence of phosphatic clays, observation of clay flocculation rates by polymers derived from these organisms, and clarity of polymer-flocculated clay suspensions. The polymer-producing organisms exhibited little capacity for flocculating phosphate and potash clay-slimes. Fungal spores of Cladosporium cladosporioides (isolated from a phosphate clay-waste impoundment), when agitated with clay-slime for several days, caused the clay to form pellets. Separation of the clay/fungal pellets (density 1.1 g ml-1) from the process water might he possible using a screening technique. Studies with C. cladosporioides included the determination of suitable energy substrates and supplements for growth, absorption studies of a pigment produced by the organism, determination of the time required for bioflocculant production by the organism, and an elucidation of the conditions required for the pelletization of clay-slimes by the fungus.

Jan 1, 1982

By Donald P. Tuchman, Robert P. Vinson, Jon C. Volkwein

Research by the National Institute for Occupational Safety and Health (NIOSH) has pursued quartz analysis for the specialized ?lter assemblies of a new worker-wearable personal dust monitor (PDM). The PDM is a real-time instrument utilizing a tapered element oscillating microbalance (TEOM®). Standard ?berglass TEOM ?lters cannot accommodate the desired P-7 infrared analytical method used by the Mine Safety and Health Administration (MSHA). Novel ?lter materials were tested with the objective of demonstrating this type of analysis. Low temperature ashing and spectrometric examination were employed, revealing that nylon ?ber candidate ?lters left minimal residual ash and produced no signi?cant spectral interference. Avoiding titanium dioxide in all ?lter materials proved to be a key requirement. Fine quartz particulates were collected on prototype ?lters in a Marple chamber, either open-faced or through PDMs during test runs. The ?lters were then subjected to MSHA P-7 analysis and the spectrometrically based analytical results for quartz mass were compared to reference measurements. Also, PDM instrumental mass readings were compared to ?lter gravimetric measurements. Results suggest that the P-7 method is adaptable to variations in ?lter materials and that quartz dust analysis by the P-7 method when utilizing the new ashable PDM ?lters can have accuracy and precision within 10% and 4%, respectively. This is within the declared 13% accuracy and 7–10% precision of the P-7 method itself. Instrument mass readings had modest positive bias but met NIOSH accuracy criteria. Continued work with specialized PDM ?lters is merited, as they are a new type of TEOM sample amenable to ashing analysis of particulates.

The mineral Industry, following the economy as a whole, experienced little growth in 1992. However, with modernized plants, efficient workforces, and lower operating costs, the industry is well positioned to take advantage of possible improvement in the national economy during 1993. In addition to the significant 1992 events highlighted below, important events, trends, and issues within individual mineral industries are addressed in the commodity sections that follow. The value of processed materials of mineral origin is estimated to have been about $310 billion in 1992. The value of U.S. raw nonfuel minerals production in 1992 is estimated at approximately $32 billion, a 3% increase over 1991. The value of domestic minerals production has increased in all but 4 of the last 32 years.

Jan 1, 1993

By Ned Baker

Details are given of a Hydride Fuel System to provide 5 kg of HZ to fuel a Caterpillar 3304 engine previously modified to operate on hydrogen fuel and intended to power an underground mining vehicle. The Fuel System was installed onto the engine and the Engine/Fuel System tested under cold start conditions and a full range of engine loads and speeds. Refueling tests were also performed. The fuel system tested will support full engine power and allow delivery of at least 3/4-power on a continuous basis, from cold start conditions.

Jan 1, 1983

By G. R. Hopkins

The average heat requirement per barrel of crude processed in the United states rose from 555,000 B. t. u. in 1939 to 579,000 B. t. u. in 1940, although crude runs increased from 1,237,840,000 barrels to 1,294,162,000 barrels in that period. Thus the almost invariable rule that the average amount of heat needed to refine a barrel of crude oil declines when total crude runs to stills increases was broken. (See fig. 1.) The reasons underlying the apparent loss in fuel efficiency in 1940 are quite obscure. There is little question but that the principle of heat exchange, the most important fuel saver, was used as extensively in 1940, as in 1939. A few companies replaced purchased power with electricity made at their plants, but for the country as a whole purchased electricity increased 7 percent, as compared with a 5-percent gain in crude run to stills. Furthermore, the premise the more complex the products the more fuel required -does not hold, as the yield of ?complex" products, including gasoline, declined in 1940.

Jan 1, 1942

By Robert L. Lagace

A whole-mine experiment to assess the practical feasibility and utility of the dedicated-wire technique for overcoming poor trolley carrier phone system performance at a large underground coal mine was designed, performed, and evaluated. The technique involves the use of a single, low-loss, properly terminated and branched auxiliary wire placed in the rail haulageway. This auxiliary dedicated wire allows signals to electromagnetically couple to the trolley wire/rail transmission line, and thereby significantly decrease the overall signal attenuation rate on the trolley wire/rail line. The in-mine dedicated-wire demonstration program and its results, conclusions, and recommendations are described. The dedicated-wire technique is shown to be a valid and practical one for significantly improving carrier phone system performance in coal mines.

Jan 1, 1981

By Willard L. Hunter

The research described in this Bureau of Minus report was conducted to improve the chromium-iron ratio of offgrade chromite. Two methods were used: (1) Iron was selectively reduced from chromite by carbothermic reduction in an electric-arc furnace, and (2) a mixture of carbon, chromite, and sometimes fluorspar was chlorinated to remove a substantial part of the iron. Chromite concentrate from the Mouat deposit in Montana and from northern California was used in the test work. Chromium-bearing slag and chromite that had been beneficiated by a roast-leach process were each smelted to produce high-carbon ferrochromium. Iron was selectively reduced in a laboratory-scale., electric-arc furnace. Carbon additions to the smelting charges varied from 40 to 100 percent of the stoichiometric requirement, and slag basicities were varied from 0.4 to 1.0 chromium-iron ratios of more than 4:1 were obtained with 89 percent recovery of chromium in a chromium-bearing slag.

Jan 1, 1962

By M. John Brodie

This report reviews the regulatory environment as it pertains to waste rock management and disposal from mining operations, excluding coal and placer gold operations, in the \irate of Alaska. It is based on the EPA's staff position on an effective program to regulate mining waste as presented in the May, 1990 Strawman II document. The unique conditions which occur in pans of the state, including a fragile environment, high seismicity and permafrost, are identified. The special waste management practices which are necessitated by these conditions are delineated. The report provides a detailed outline of the current technologies that are suitable for designing, constructing, operating and closing a waste rock facility to meet environmental protection objectives. Cost implications to the mining industry of potential regulatory actions, such as the degree of groundwater protection, are examined.

Jan 1, 1992